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Credit: Matt Rogers, Century West Engineering

In combination with the porous asphalt pavement, rain gardens in swales can manage 100 percent of a site's stormwater.
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Credit: Matt Rogers, Century West Engineering

Porous asphalt allows for a great deal of infiltration, providing onsite storm-water management and reducing storm surge into adjacent waterways.

Sustainable design has been a buzzword for the past few years, but the Port of Portland (Ore.) has taken it to a new level with a porous pavement project. Built in 2006, the Port installed 35 acres of porous asphalt, along with 15 acres of impervious pavement, at one of its automotive-import facilities.

The Terminal 6 project provides a model of environmental stewardship and smart business, balancing benefits to the community, the economy, and the environment.

At an estimated construction cost of $6.45 million, the developed area will save the Port money in the short and long run.The agency saved $250,000—and nearly a year of time—on its National Pollutant Discharge Elimination System permit, which regulates and keeps tabs on stormwater runoff for a given area. “Since there were no assets to build underground, it was faster and cheaper,” says Dave Dittmer, engineering project manager at the Port.

The Port also receives a discount on the city's storm sewer fee for using porous pavement. The area has unique sub-surface conditions; it is mostly sand, which allows for better infiltration. This sub-surface eliminates the need for underground piping systems to remove the stormwater runoff—another cost savings.

Maintenance includes sweeping the area a couple of times per year, which is typical for porous pavement. Since the facility is for new cars, there are no fluid leaks to worry about. “This is a unique situation,” Dittmer says. “It's not common for other public works departments to have a situation like this where no containment is needed.”

The Oregon chapter of the American Public Works Association recently awarded the project a Julian Prize for Sustainability. The Port hired Portland-based Century West Engineering and landscape architecture firm GreenWorks, along with stormwater management firm Cahill Associates, West Chester, Pa., to complete the project.